Combining desirable difficulty learning strategies to address the amount-to-learn vs. time-to-learn imbalance in residency training.

Purpose: Residents have limited time and much to learn. Mounting evidence shows that Desirable Difficulty (DD) learning strategies can ease that imbalance, but few studies have specifically studied combinations of these strategies.

Methods: We tested two different combinations of DD strategies: a double combination of distributed practice and retrieval practice and a triple combination additionally including interleaved practice. We compared residents' annual In-Training Exam (ITE) scores and graduates' board certification performance between both DD curricula and a historical baseline.

Results: Average ITE scores rose from 149.06 in the historical baseline to 160.04 under the combined DD curricula ( < 0.001). Average ITE scores fell from 162.50 under the double combination to 155.11 under the triple combination ( = 0.03). There were no significant changes in graduates' board performance between any of the curricula.

Conclusions: These results add to the evidence that DD strategies can enhance residents' learning. The drop in ITE scores under the triple DD combination may suggest that it pushed learners past beneficial difficulty into detrimental overwhelming difficulty. Further research should apply this framework in larger and more diverse settings to clarify how these DD strategies can be optimally used to enhance residents' learning.